A federal watchdog has launched an investigation into Texas Republican Sen. Ted Cruz over a $35 million COVID relief loan given to billionaire fracking brothers who were also top Cruz campaign contributors, Bloomberg reported .

Dan and Farris Wilks received the taxpayer-backed windfall even though their businesses were flush enough at the time to buy stakes in six other fracking companies, The Wall Street Journal reported late last year.

Cruz reportedly helped persuade then-Treasury Secretary Steven Mnuchin and the Federal Reserve to change the rules for the Main Street Lending Program to include operations like the Wilks businesses. The brothers then obtained a $35 million low-interest loan for ProFac Holdings LLC, a supplier of pumping equipment and services, according to records.

The Wilks brothers also donated $15 million to the super PAC Keeping the Promise, which backed Cruzs 2016 presidential campaign.

The federal inquiry led by Special Inspector General for Pandemic Recovery Brian Miller was revealed in his offices quarterly report that was released Monday, Bloomberg reported. In the report, Miller referred to reporting that raised questions about the senators successful push for changes in the loan program to ensure access to capital for the oil and gas industry.

While it does not allege misconduct, it does concern management of the investments by Mnuchin, Miller wrote in a letter last month to Brian Callanan, general counsel for the Treasury Department, which was included in the quarterly report.

Miller requested all correspondence between Cruz and Mnuchin concerning the changes to the lending program, a list of companies affected by the modifications, details of the loans granted and the rationale for the changes.

Cruzs office did not immediately respond to a request for comment from HuffPost. However, his office defended the Wilks brother loan to the Journal after the publication of its story, saying the senators work for fossil fuel industries protected 300,000 jobs amid the pandemic.